Generally, roads produce splits and unevenness over time due to the passing of vehicles, and the like, and such splits and unevenness need to be repaired. In order to repair such roads, the road is inspected, and data on road surface property of the road, that is, data on a state of unevenness of the road surface are acquired. The data on the road surface property are acquired by measurement carried out by measuring personnel, or by causing a road surface property vehicle to travel along a predetermined path of a road to be measured. A device for irradiating a road surface with a scan light, and measuring a height of each point of the road surface is mounted on the road surface property vehicle.
Japanese Unexamined Patent Publication No. 10-288516 (hereinafter referred to as Patent document 1(A)) describes a device that projects light toward a plane while moving a moving body in a longitudinal direction of the plane, and measures a step difference of the plane according to the light projection result, the device having a configuration of including a means for detecting a moving distance, a light projecting means, a means for imaging a light irradiation line, a transverse direction data computing means for acquiring height data, a vertical direction data computing means, and a three-dimensional data computing means. According to such configuration, a technique in which the light is projected toward a plane RD from a moving body so that one irradiation line forms on the plane RD along a transverse direction W of the plane RD every time the moving body moves a predetermined distance, and an unevenness profile is acquired in real time by the various types of means is described.
However, causing the vehicle to travel on all lines of the road to be subjected to maintenance requires great trouble and time. Furthermore, since the road surface property vehicle is expensive, it is costly to carry out the measurement on all the lines.